In the production of metallic layers on substrates the aim generally is to obtain preferably smooth and high gloss coats. But depending on the specific application, it is frequently desired to obtain a metal coat which is not glossy but matt. The reason for that may be the optical appearance of this coat, and also the technical properties, i.e. the nonglaring of such coats. Fields of application for matt deposited metal layers on substrates are for instance the jewelry industry, fittings industry, automobile industry, but also the optical and precision industry, where especially the nonglaring of these coats is important. From prior art matt deposited nickel or nickel alloy layers as well as cobalt layers are known. While the deposition of such potentially allergy-causing metals is noncritical in many fields, it is desirable to avoid these metals in the field of the jewelry industry or also in the field of kitchenware and kitchen utensils. Within the field of the optical or precision industries the deposition of matt metal layers of the most different metals is desirable because of the different properties of the respective metals. In addition, it is desirable to be able to adjust the degree of mattness of the deposited metal layer over a vast range. It is an object of the present invention to provide an electrolyte as well as a process for depositing matt metal layers on substrates, by which method a variety of metals can be deposited with different degrees of mattness on the most different substrates.
Briefly, therefore, the invention is directed to an electrolytic composition for the deposition of a matt metal layer onto a substrate and deposition process where the composition comprises a source of metal from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, In, Sn, Sb, Re, Pt, Au, Bi, and combinations thereof; a substituted or unsubstituted polyalkylene oxide or its derivative as an emulsion and/or dispersion former; and a compound comprising fluorated or perfluorated hydrophobic chains or which is a polyalkylene oxide substituted quaternary ammonium compound as wetting agent; wherein the electrolytic composition forms a microemulsion and/or dispersion.
Other objects and features of the invention will be in part apparent and in part pointed out hereinafter.